On Fri, Aug 23, 2024 at 03:08:55PM +0200, Andi Shyti wrote:
> Create the 'ccs_mode' file under
>
> /sys/class/drm/cardX/gt/gt0/ccs_mode
>
> This file allows the user to read and set the current CCS mode.
>
> - Reading: The user can read the current CCS mode, which can be
> 1, 2, or 4. This value is derived from the current engine
> mask.
>
> - Writing: The user can set the CCS mode to 1, 2, or 4,
> depending on the desired number of exposed engines and the
> required load balancing.
>
> The interface will return -EBUSY if other clients are connected
> to i915, or -EINVAL if an invalid value is set.
This does not agree with the code. The code is a _lot_ more clever.
-Sima
>
> Signed-off-by: Andi Shyti <andi.shyti@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/gt/intel_gt_ccs_mode.c | 82 ++++++++++++++++++++-
> 1 file changed, 80 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_gt_ccs_mode.c b/drivers/gpu/drm/i915/gt/intel_gt_ccs_mode.c
> index cc46ee9dea3f..1ed6153ff8cf 100644
> --- a/drivers/gpu/drm/i915/gt/intel_gt_ccs_mode.c
> +++ b/drivers/gpu/drm/i915/gt/intel_gt_ccs_mode.c
> @@ -6,6 +6,7 @@
> #include "i915_drv.h"
> #include "intel_engine_user.h"
> #include "intel_gt_ccs_mode.h"
> +#include "intel_gt_pm.h"
> #include "intel_gt_print.h"
> #include "intel_gt_regs.h"
> #include "intel_gt_sysfs.h"
> @@ -172,7 +173,7 @@ static int rb_engine_cmp(struct rb_node *rb_new, const struct rb_node *rb_old)
> return new->uabi_class - old->uabi_class;
> }
>
> -static void __maybe_unused add_uabi_ccs_engines(struct intel_gt *gt, u32 ccs_mode)
> +static void add_uabi_ccs_engines(struct intel_gt *gt, u32 ccs_mode)
> {
> struct drm_i915_private *i915 = gt->i915;
> intel_engine_mask_t new_ccs_mask, tmp;
> @@ -230,7 +231,7 @@ static void __maybe_unused add_uabi_ccs_engines(struct intel_gt *gt, u32 ccs_mod
> mutex_unlock(&i915->uabi_engines_mutex);
> }
>
> -static void __maybe_unused remove_uabi_ccs_engines(struct intel_gt *gt, u8 ccs_mode)
> +static void remove_uabi_ccs_engines(struct intel_gt *gt, u8 ccs_mode)
> {
> struct drm_i915_private *i915 = gt->i915;
> intel_engine_mask_t new_ccs_mask, tmp;
> @@ -273,8 +274,85 @@ static ssize_t num_cslices_show(struct device *dev,
> }
> static DEVICE_ATTR_RO(num_cslices);
>
> +static ssize_t ccs_mode_show(struct device *dev,
> + struct device_attribute *attr, char *buff)
> +{
> + struct intel_gt *gt = kobj_to_gt(&dev->kobj);
> + u32 ccs_mode;
> +
> + ccs_mode = hweight32(gt->ccs.id_mask);
> +
> + return sysfs_emit(buff, "%u\n", ccs_mode);
> +}
> +
> +static ssize_t ccs_mode_store(struct device *dev,
> + struct device_attribute *attr,
> + const char *buff, size_t count)
> +{
> + struct intel_gt *gt = kobj_to_gt(&dev->kobj);
> + int num_cslices = hweight32(CCS_MASK(gt));
> + int ccs_mode = hweight32(gt->ccs.id_mask);
> + ssize_t ret;
> + u32 val;
> +
> + ret = kstrtou32(buff, 0, &val);
> + if (ret)
> + return ret;
> +
> + /*
> + * As of now possible values to be set are 1, 2, 4,
> + * up to the maximum number of available slices
> + */
> + if (!val || val > num_cslices || (num_cslices % val))
> + return -EINVAL;
> +
> + /* Let's wait until the GT is no longer in use */
> + ret = intel_gt_pm_wait_for_idle(gt);
> + if (ret)
> + return ret;
> +
> + mutex_lock(>->wakeref.mutex);
> +
> + /*
> + * Let's check again that the GT is idle,
> + * we don't want to change the CCS mode
> + * while someone is using the GT
> + */
> + if (intel_gt_pm_is_awake(gt)) {
> + ret = -EBUSY;
> + goto out;
> + }
> +
> + /*
> + * Nothing to do if the requested setting
> + * is the same as the current one
> + */
> + if (val == ccs_mode)
> + goto out;
> + else if (val > ccs_mode)
> + add_uabi_ccs_engines(gt, val);
> + else
> + remove_uabi_ccs_engines(gt, val);
> +
> +out:
> + mutex_unlock(>->wakeref.mutex);
> +
> + return ret ?: count;
> +}
> +static DEVICE_ATTR_RW(ccs_mode);
> +
> void intel_gt_sysfs_ccs_init(struct intel_gt *gt)
> {
> if (sysfs_create_file(>->sysfs_gt, &dev_attr_num_cslices.attr))
> gt_warn(gt, "Failed to create sysfs num_cslices files\n");
> +
> + /*
> + * Do not create the ccs_mode file for non DG2 platforms
> + * because they don't need it as they have only one CCS engine
> + */
> + if (!IS_DG2(gt->i915))
> + return;
> +
> + if (sysfs_create_file(>->sysfs_gt, &dev_attr_ccs_mode.attr))
> + gt_warn(gt, "Failed to create sysfs ccs_mode files\n");
> }
> --
> 2.45.2
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
